Lift bar mechanism for window blinds



Jan. 30, 1951 H. F. HACKEDORN, JR

LIFT BAR MECHANISM FOR WINDOW .BLINDS Filed April 5, 1949 2 Sheets-Sheet 1 INVENTOR. m4 us F- HAG/(5.270757% .m

A TTOIP/VE Y5 Jan. 30, 1951 H. F. HACKEDORN, JR

LIFT BAR MECHANISM FOR WINDOW BLINDS 2 Sheets-Sheet 2 Filed April 5, 1949 ATTORNEYS INVENTOR. HILL /5 FTHAC/(fDOiP/WR f atented jan. 30,

UNITE D ST TES NT ()FFlCl-Ei LIFT BAR MECHANISM 1 R WINDOW BLINDS" Claims? This invention relates to Venetian or other types'of windowblinds 'of the type that'ar'eraised and lowered by manua'lmanipulation of a bottom lift bar and m'oreparticul'arlyto an' automatic locking orbraking mechanismforthe lift bar.

My improved lift bar lock mechanism is adapted to be disposed internally of the liftbar and to operate in conjunction with the lift bar" for permitting relatively free" manual upward movement of the bar during raising of the blind While automatically preventing downward o'r" lowering movement of the bar to holdsame'in' any adjusted position. Accordingly; it is among the objects of my invention to provide'a rugged; inexpensive and efiicient lift bar locking mechanism that willautomatically prevent downward movement of the lift bar except when manually released but will permit free upward movement thereof at all times.

Another object of my invention is to provide a compact self -locking and self-releasing lift'bar lock mechanism which may be-fabricated as a sub-assemblyunit and conveniently" assembled on the job when the blind is beinginsta'lled.

These and other objects of my inventionw-ill appear from the following description of an" em: bodiment thereof; reference being hadto the accompanyingdrawings in which:

Figure 1"- is' an elevation of a Venetian blind assembly and-a window frame; my improved lock or brake being incorporated-'in'the lift bar Figure 2 isan enlarged fragmentary side eleva tionof a portion of the lift bar;

Figure 3 is an-enlarged vertical cross-sectional view of the central'portion of'my lift bar, illus: trating thebrake' or lock-'in locked position and T taken substantially on the line 3-3 of Figure 4:;

Figure 4 isacross-sectionalv view taken substantially on line 4-4 of'Figure 31' Figure 5 is a detached perspective-view of thelock unitguide piece;

Figure 6 is a perspective View of the central portion of the lift-bar which houses my'lock mechanism;

Figure '7 is a detached side elevation of the Y cam member;

Figure 8 is an endview of Figure '7 with the" upper portion of the cam member shown; in' cross-section;

Figure 9 is a longitudinalcross sectional- View of. the hub element;

FigurelO is'a sectional view of the hub element takennsubstantially on line l0l0 of Figure 9'; and:

Figure; 11 .is: a: detached side elevational view of the lock releaselever with a portion of the shank or hub thereof shown in cross-section.

Referring'now to Figure l', .reference character" i designates a, Window frame with which a Venetian' blind- 2 isassociated. The Venetian blind 2 in which I have incorporated myi presentinventio'n'is of the sci-called cordless type and in"- cludes'a hea'd boxiimounted at the upper edge of the window frame 5. A suitable slat tilting I and tape supportingmeananot shown in detail',

is housed in the head'box-3 and the lower of the tapes are securedto the tubular lift bar fi whicl'i will'be more fully described later.

The tapes 4 support the slats 6 in' the usual'. and well known manner and the tilt cords T; which operate the" tilt mechanism in the head box i, provide the means for manually tilting the" slats 6'; Since the slat supporting tilting" mechanism'may'be of anysuitable type and as it is not, perse, a partof the present invention, I have not described it in'detail.

Side channel members 8and 9 are'secur'ed to opposite sidesof thewindow frame I and are" adapted to receive the end portions lo and H respectively of the lift bar 5 for guiding sameduring verticalmovem'ent. Portionsof'the guide tapes i2 and 13 are also disposed within" the" channel" members 8 and 9 and may be of any" suitable type such as fabric; flexible metal; etc; Tape l2 iss'upp'orted at' its'u'pper end bya'clip" lt, see Figurel, located'near the upper end of" channels, and extends downwardly within Chan'- nel 8, passesthrough the tubular lift bar 5" from left to right and out of the right hand (Figure l) end-thereof; and-finally is connected at its lower end to a clip {5' atthe-lower'end'of'chan nel 9. In like manner'guide'tape i3 is*connected" toclip l8 located near the upperendof channel 9; passes downwardly within sideehannel mem-' ber'9, enters'the rightend (Figure l) of the lift" bar 5; passes out of the left' -end thereof, and is anchored at its lower end-'to-clip ll at the bottom of the channelB. The manner inwhich the guide tapes' l 2 and i3 operate in conjunction" with the liftba'r Biwill lie-explained more fully later;

The'li'ft bar 5 comprises-an assembly ofidentical'end portions Hl and H whichtelesc'ope into the opposite endofa central body portion l9 as clearlyshown inFigur'es 1"and 2. The central body portion l9 of the liftbar hasfl'uted orribbed side walls for providing greater rigidity and strength in the unit, see Figure 6; and the end portions m and II are secured in position'by means of screws-2 B and-2 whichextendthrougii slot 22 in the bottom of the central body portion I9, see Figure 6, into threaded holes in end portions In and II. These detachable end portions I6 and II permit the section I9 to be cut to the proper length to fit the window on which the blind is installed.

The end portions I and I I of the lift bar have pairs of guide rollers 23 and 24 and 23 and 24' respectively, which are rotatably supported at the outer ends of portions I0 and II and over which the guide tapes I2 and I3 pass as they enter and leave the lift bar 5. Guide rollers 23 and 24 are rotatably mounted on shafts 25 and 26, Figure 2, and rollers 23' and 24' are similarly mounted. The roller shafts are disposed to extend transversely of the end portions I0 and II and insure that minimum friction will be offered to the guide tapes I2 and I3 as bar 5 is raised or lowered. The end portions I0 and II are identical in all respects and may be interchanged and reversed end for end if desired.

The central body portion I9 of the lift bar 5 is adapted to receive a lock unit mechanism generally indicated at 28 in Figures 1 and 2, and shown on an enlarged scale in Figures 3 and 4. It is well to note at this point, that the guide tapes i2 and I3 must cross each other within the lift bar, as will be described in more detail later, and pass through the lock unit 28 in which they are acted upon by elements thereof in a manner to be described shortly. The central body portion I9 is provided with screw holes 29 and 30, see Figure 6, which are adapted to receive securing screws 3I and 32 for holding the lock unit 28 in position.

The lock unit 28 is a sub-assembly which is insertable as a unit in the hollow central body portion I9 of the lift bar 5. It includes a guide piece, generally indicated at 33, see Figure 5, by which the individual parts of the locking mechanism are supported and which has substantially parallel side walls 34 and 35, end walls 36 and 31, and a bottom wall or tape supporting plate 38. Side wall has an aperture 39 located near its upper central portion and wall 34 has a similar but reduced aperture 40 located near its upper central portion and aligned with aperture 39. Each of the end walls 36 and 31 have inwardly struck guide tape tangs, M and 42 respectively, located near the bottom portion of each end wall. The tangs 4i and 42 extend substantially parallel to the tape supporting plate 38 and define therebetween openings 43 and 44 respectively, through which the guide tapes i2 and I3 pass when the lock unit mechanism 28 is assembled within the body portion I9 of the lift bar 5. The innermost end of each tang is bent upwardly as'indicated at 45 and 46 respectively to provide smooth surfaces against which the tapes may rub and to eliminate the possibility of snagging of the top tape on the tang ends. End wall 35 is also provided with a transverse slot 41 and a vertically extending notch 48 located approximately at mid-height thereof for anchoring one end of spring I6 of the locking mechanism as will be explained later.

Disposed between the side walls 34 and 35 of the guide piece 33 is cam member 50 which is shown assembled in the lock unit 28 in Figure 3 and detached in Figures 7 and 8. The cam has a solid bottom body portion 5I and a, U- shaped upper portion 52. The U-shaped portion 52 is made up of two upwardly extending substantially parallel side walls 53 and 54 and top surface 55 of the bottom portion 5i, see

Figure 8. Walls 53 and 54 are provided with aligned apertures 56 and 51, the axis of which constitutes the axis of rotation of the cam member 50. The apertures 56 and 5! are substantially circular with the exception of a fiat portion designated 58, see Figure 7, which constitutes a keying means for non-rotatably mounting the cam member 56 on hub 63 as is described more fully below.

The bottom portion 5I of cam member 56 is provided with an irregularly curved cam surface 60 which is clearly shown in Figures 7 and 8. The profile configuration of surface 66 is such that the radial distance from the center of rotatlon progressively increases from substantially a minimum at a point 52 on the right side of the surface as viewed in Figure 7 to substantially a maximum at point 6I on the left side thereof.

Cam member 59 is supported within the side walls 34 and 35 of guide piece 33 by means of a hub 63, shown clearly in Figures 4, 9, and 10, which is rotatably supported at its ends in apertures 39 and 46 of the side walls 35 and 34, respectively, of the guide piece 33. The hub 63 has a reduced end 64 which fits into the hole 40 of the guide piece 33. The shoulder 64a abuts the inner face of wall 34 and prevents axial movement of the hub 63 to the left (Figure 4.) when the parts are assembled. The hub also has a bearing portion 65, whose external surface is substantially cylindrical except for a flat portion 66, is rotatably supported in aperture 39 of guide member 33 and the flat portion 66 of the hub is oriented to engage the flat portions 58 and 59 of apertures 56 and 51 in cam member 59, so as to key the hub 63 and the cam member 50 together.

The external surface of bearing portion of the hub 63 is also provided with an annular groove 61 for receiving spring clip 68 which serves to hold the hub in assembled position within the side walls 34 and 35 of the guide piece 33 (see Figures 3 and 4).

A tapered recess 69 in the bearing portion 65 of the hub 63 is adapted to receive the complementary tapered shank T6 of release lever Ii shown in Figure 11. The shank I0 has a central bore I2 through which a threaded securing screw I3 extends. When screw i3 is threaded into the threaded hole I4 in the reduced end 64 of the hub 63 the shank ID will be drawn into tight non-rotatable engagement with the tapered surface of recess 69 of hub 63. The lever II is preferably counter bored at I5 (see Figure 4) in order to receive the head of the securing screw I3.

A looped wire spring I6 is disposed about the hub 63 and has two pressure arms I! and I8 which engage the guide piece 33 and the cam member 56 respectively whereby to exert a constant pressure upon the latter tending to rotate it in tape locking or jamming direction (counterclockwise as seen in Figure 3). Spring arm 1! is adapted to fit into the notch 48 of recess 41 in the end wall 36 for easy assembly and arm I8 bears against bottom portion 55 of the cam member 56.

As heretofore mentioned, guide tapes I2 and I3 extend through the guide piece 33, entering and leaving the same through openings 43 and 44 at each end thereof. Since each guide tape extends from an upper corner of the window frame through the lift bar 5 to the lower corner of the other side of the window frame, they nee;

essarily cross each other at some point Within. the lift bar The cross over point isindicatedu at T9 in Figure 2 and is located to the left of the guide piece 33. Thus; as the tapes enterthe left opening 43 in the guide piece" they will be" arranged in a superimposed vertically aligned re-- lation, with tape !3 on top of tape [2. The superimposed relation between guide tapes [2 and I3:

exists as long as the tapes are'within the walls of the guide piece 33. A passage to is formed between the peripheral surface 69 of the cam member 58 and the tape supporting plate 38 of the guide piece through which guide tapes l2 and I3 extend. The peripheral'surface' 6!]: of cam member 58 is urged into engagement with the top tape l3 by the action of spring 16 (see Figure 3) and in this manner contact between the top tape [3 and the cam member 58 is nor-- mally maintained.

The-automatic locking action of-the cam member 50 on the tapes takes place as follows: As the lift bar is raised the guide tape [3 will have move ment to the left (Figures 1, 2 and 3) relative to the bar 5. Movement of tape it in this direction: will produce a tangential force on cam surface" When upward movement of lift bar 5 is stopped and lifting force removed therefrom it tends to move downwardly under the influence of gravity. As soon as it starts down, however, the relative movement of the guide tapes l2 and I3 with respect to the guide piece 33 isreversed from that just described, that is, guide tape l3 will move toward the right, as viewed in Figures 1 and 3, and tape I2 will move to the left. The effect of such movement of the top tape I3 to the right when passing under and invcontact with cam surface 60 is to rotate the cam member fill in a counter-clockwise tape locking or jamming direction. This rotation of the cam member 5-- diminishes the height of passage 8!! through which the guide tapes pass and effects a wedging or jamming together of the guide tapes between cam surface 60 and bottom wall 38 of the guide piece; This wedging action is effective to lock the parts against further movement of the guide tapes relative to lift bar 5 and thus lowering movement of the lift bar and window blind is prevented.

Lowering of the lift bar 5 and blind assembly can be accomplished whenever desired by urging, as by thumb pressure of the operator, release lever H upwardly as viewed in Figure 2. Since the release lever is non-rotatably locked to the hub 63, which in turn is keyed to cam member 5i], upward movement of the lever H from the position shown in Figure 2 causes a clockwise rotation of the cam member and, as explained above, will permit the guide tapes to move freely between cam surface 66 and the tape supporting plate 38 of the guide piece. As soon as lever H is released by the user, spring 16 will act against the cam member 56 to rotate the same into engagement with the top guide tape whereby to bring the automatic one way locking system described above into operation.

My improved lift bar lock mechanism contemplates a sub-assembly unit which is made up of all the parts carried by guide memberi33 except? operating lever 1 I During installation of. a blind the tapes i2 and. I3 are positioned in this subassembly as seen in Figure 3 and the sub-assem bly then located in the body portion 9' of bar 5, by sliding it in from one end, with hole 39 adja cent and aligned with hole 39 (see Figure 4).. Next the shank T0 of lever H is passed through' hole 39' into tapered bore 69 of hub 63, lever H set at the desired angular position, and then screw 13 inserted and tightened to lock the lever to the hub 63 so that it will operate cam 58. This:

ticularity, it will be understood that I do not wish.

to be limited to the particular mechanism herein shown and described and that various changes.

can be made to the illustrated form of my apparatus without departing from the spirit of my invention. For example, guide tapes [2 and 3,-

although illustrated herein as fiat fabric tapes, could be made in the form of chains, flexible wire cables, or the like, and cam surface 68 could be suitably surfaced to properly engage same. I therefore claim as my invention all embodiments thereof coming within the scope of the appended claims.

I claim:

1. In a lift bar for a Venetian blind or the like comprising a tubular body member, a guide piece removably disposed within said tubular member and having side walls and a bottom wall, said sid walls have aligned apertures near the top thereof, guide tapes extending through said guide piece in superimposed relation adjacent the bottom wall thereof and movable with respect thereto and to each other as said lift bar is raised and lowered, a hub element rotatably mounted in said apertures, means for retaining said hub element in said apertures, a cam member carried by said hub element for rotational movement therewith and having a cam surface disposed to' engage one of said tapes, spring means for nor mally holding said cam surface in engagement with said one of said tapes, said one of said tapes being adapted to urge said cam member to rotate into jamming relation to said guide tapes as said lift bar is lowered while urging said cam member to rotate out of jamming relation to said tapes as said lift bar is raised, and manually operable means projecting from said tubular member for moving said cam member out of jamming relation to said tapes.

2. In a lift bar for Venetian blinds or the like, a tubular body member, a cam member rctatably supported within said body member, said cam member having a tape locking cam surface the radial dimension of which progressively increases from a minimum to a maximum, a tape supporting plate spaced from said cam surface, the axis of rotation of said cam member being substantially parallel to said supporting plate whereby rotation of said cam member will cause the space between said cam surface and said supporting plate to increase or diminish, means for directing a pair of guide tapes through the space between said cam surface and supporting plate in superimposed relation, spring means for urging said cam member to rotate in one direction to reduce said space between said cam surface and said supporting plate, and manually operable release means ncn-rotatably and removably connected with said cam member and. projecting from said tubular body member, said release means being adapted to move said cam member in a direction opposite said one direction to increase said space between said cam surface and said supporting plate.

3. In a lift bar for a Venetian blind or the like comprising a tubular body member, a guide piece removably disposed within said tubular member and having side Walls and a bottom wall, a hub element rotatably supported by the side walls of said guide piece, a cam member carried by said hub element for rotational movement therewith, said cam member having a tape locking cam surface the radial dimension of which progressively increases from a minimum to a maximum, the axis of rotation of said cam member being substantially parallel to said bottom wall of the guide piece and said cam surface being spaced from said bottom wall whereby rotation of said cam member will cause the space between said cam surface and said bottom wall to increase or diminish, guide tapes extending and passing through the space between said cam surface and said guide piece bottom wall in superimposed relation, means for urging said cam member to rotate in one direction to reduce said space between said cam surface and said bottom wall, and a manually operable release lever projecting from said tubular body member and having a shank disposed in non-rotational engagement with said hub element whereby said lever is adapted to move said cam member in a direction opposite to said one direction to increase said space between said cam surface and said bottom wall.

4. In a lift bar for a Venetian blind or the like comprising a tubular body member, a guide piece removably disposed within said tubular member and having side walls and a bottom wall, a hub element rotatably supported by the side walls of said guide piece, said hub element having a recess therewithin, a cam member carried by said hub element for rotational movement therewith, said cam member having a tape locking cam surface the radial dimension of which progressively increases from a minimum to a maximum, the axis of rotation of said cam member being substantially parallel to said bottom wall of the guide piece and said cam surface being spaced from said bottom wall whereby rotation of said cam member will cause the space between said cam surface and said bottom wall to increase or diminish, guide tapes disposed within said space in superimposed relation, means for urging said cam member to rotate in a direction to reduce said space between said cam surface and said bottom wall, and a manually operable release lever projecting from said tubular body member and having a shank, said shank being removably disposed face and the other with said bottom wall of the guide member, spring means for urging said cam member into locking engagement with said one of said tapes, said cam member having an unlocked position near one limit of rotation thereof whereby to permit free upward movement of the lift bar and a locked position near the other limit of rotation thereof whereby to prevent downward movement of the lift bar, and manually operable means projecting from said bar and non-rotatably connected with said cam member for moving same to said unlocked position.

' HILLIS F. HACKEDORN, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Name Date Nottingham July 8, 1941 Num er 

